Such groups R1 after attachment form ester or ester type groups so that R1 is actually an aliphatic or aromatic group such as R, but is preferably limited to aliphatic groups of 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, and most preferably 1 to 4 carbon atoms for aliphatic groups and 1 to 10 carbon atoms for aromatic groups.